Variable speed drive for machine tools



June 27, 1933. w. FERRls VARIABLE SPEED DRIVE FOR MACHINE TOOLS FiledApril 25, A1927 -4 sheets-sheet v1` June 27, 1933. w. FERRIS VAELEEIJESPEED DRIVE FOR MACHINE TooLs Filed April 25, 1927 4 Sheets-Sheet 2 AIMI sa INVNTR. l/IIL'TEE @$525.

ATTORNEY.

June 27, 1933.

W. FERRIS VARIABLE SPEED DRIVE FOR MACHINE TOOLS Filed April 25, 192'? 4Sheets-Sheet 3 INI/EN TOR.

WALTER ERE/5.

ATTORNEY.

X June 27, 1933.

W. FERRIS VARIABLE SPEED DRIVE FOR MACHINE TOOLS Filed April 425, 1927 4Sheets-Sheet 4 5% a V W l I r A N V EN T 0R. W41: TEE 755525.

TTRNEY.

`rammed.June 27,193.1',

UNITED vsrivrlazs WALTER EERRIS, OF MILWAUKEE,

WISCONSIN, AssIGNon rro THE oILGm COMPANY, n

' 0F MILWAUKEE, WISCONSILL A CORPORATION DF WISCONSIN vanierm2 SPEEDDarrin ron MACHINE 'rooLs Application led April 25,

This invention relates to variable speed drives for machine tools andthe like.

For purposes of description and explanationan embodiment of the presentinvention 5 will be described as applied to a multiple turret lathealthough certain of the novel features thereof may be advantageouslyemployed in machines of variousv other types. The rate of relativemotion between the v Work and tool inthe direction of the cutting actionis of importance from the standpoint of mechanicaleiiiciency andsmoothness of cut, and the rate selected is ordinarily governed by thecharactei` of the material operated upon, the material of which the toolis made andthe nature `of the. out'. In performing a facing Work againstthe tool during the slow ad- Vance of the 'tool across the face Iof thework,` the cutting speed normally varies, due to the varying distance/between' the tool and the axis of rotation. In an eort to approximatealconstant cutting speed,' attempts have heretofore been made to varythe rotating speed by driving the work spindle through" mechanicalchange speed gear sets of various types. ,Duej the step by stepcharacter of the speed variation obtainable by mechanical f change speedgears and because of the limited speed range ordinarily Y provided by.such mechanismsthese prior'eiorts to obtain constant cutting speeds inall positions of the tool relativetothe axis of rotation have not Yproven entirely satisfactory; v .'One object of the present invention isthe Y provision of, a variable speed drive mecha-` nism-capable ofeiecting a substantially uniform variation in operating'cspeeds throughanY unusually wide range; This I have ac- 40 complished bythe use of 'aplurality of separate variable. speed' transmissions com-- bined, toincrease the speed range, one ofs 'them possessing theproperty ofproducing a substantially uniform speed variation and L coordinatedwith`the other lin such manner as to eiect a uniform variation throughoutAthe extended range. Y'

y In thiscombination lI4 prefer-'to use a *variable speed hydraulictransmission of a- 0 well known type involving a variable speedYtherspeed range,

cut, as in a lathe, by lrotatingthev transmission' and a uniformvariable speed .transmission of means 1927. seriai No. 186,554.

motor driven by a solid column of liquid supphed from a constant speedpump, although other types of motors capable of operating at variablespeeds might be employed. When a hydraulic motor is used I prefer tovary the speed thereof primarily by regulating motor displacement, tothereby permit the pump to operate at full capacity throughout althoughchanges in pump displacement may be. resorted to to thereby furtherincrease the speed range. By the use v of'a hydraulic transmission ofthe type mentionedcombined and properly coordinated `with a mechanicalchange speed gear set, it is possible to greatly reduce the number ofseparate gear changes required in lathe spindle Adrives heretofore used,to greatly 1ncrease the speed range and to obtain a smooth variation inspeed throughout the increased range. l v 7.0

Another object ofthe present invention is the provision in a variablespeed drive mechanism involving a step by step variablev speed- :Eor socoordinating 75 said transmissions as to effect a substantial- Yly'uniform variation in speed throughout a wide range. Another object ofthe present invention is the provision lof Huid actuated' means foreffecting he change speedrfimctions of aA mechanicalchange speed gearset. l

Another object of the present invention is *the provision in amechanical change speed gear set'of mans for automatically rendering thedrive mechanism for 'said set momentarily inactive during .each speedchanging period. A

Another object is the .provision a machine tool of a variable speed.drive automatically operable to a tially constant cuttingspeed .with theat various-distances froml the axis of tation..l o l Other objects andadvantages will appear from the following description of an illusytrative embodiment of the present invention.

Infthe drawings Figure 1 is a horizontal sectional of a headstock of a'lathe equippedv witha f zal,

different operating positions.

Fig. 7 is a detail view of the mechanism employed for operating thecontrol valve.

Fig. 8 is a sectional view of nthe motor control valves of Figure 3,showing the s'ame in different positio Fig. 9 is a similar view of-oneofthe valves in. a third position.

Fig. 10 is a detail view of a cam roller.

Fig. 11 is a face view, on a larger scale, of the cams shown in Figure1.

For purposes of illustration and explanation an embodiment of thepresent invention is shown applied to a multiple turret `lathe of a wellknown type. The lathe shown includes the usual spindle l0 journaled inthe head stock 11, and carrying a chuck 12 above and adjacent one end ofthe customary ways 13. A cross-slide conventionally shown at 14 ismounted for tra-vel along the ways 13 toward and fromthe chuck in `theusual manner. The ways-also constitute a support and guide H:iortheusual turret carriage (not shown) upon which a series of tools, one oflwhich is-shown at 15, are ordinarily mount- `ed. .A tool carriage 16,supporting the usual turret 17, ismounted for travel lengthwise v of thecross;sl-ide, and is driventhrough the usual mechanism (not shown) froman appropriate gear 18 on the spindle l0.- In this instance a cuttingtool 19 is shown clamped in the turret 17 so as to travel across theface of a work piece a during rotation of the Work with and by the chuck12.

The spindle is driven by novel means capable of effecting' `asubstantially uniform variation in. rotating speeds throughout a c widerange. Provision is also madefor co- I ordinating-the variationinrotating speeds 20 havng'three gears 21, 21', and 21" the lathe shown.by

with the variation in. distance between the cutting tool 19 andthecenter of rotation, so that the actual cutting speeds may besubstantially the same in all positions of the tool. Thesefunctions areaccomplished, in mechanism such as will now be described. v n Thespindle 10 driven from a shaft 20 through a plurality'of gear setsselectively operable to establish various speed ratios betweenthe shaftand spindle. In this instance three such gear sets are provided, theshaft A spljned thereon and selectively shiftable intointermeshingrelation with three gears 22, 22', and respectively, fixedon the Spindle Gears 21 and 21 carry' flanged collars 23 and 23fashioned in a well known manner to receive the forked ends 24 and 24'.,respectively, of appropriate shifting arms 25 and 25. A third shiftingarm 25" is forked at one end 24 to embrace thesmall gear 21". The con-rtrol arms 25, 25 and 25 are formed at their other ends with sleeveportions 26, 26 and 26" slidably mounted upon separate control rods 27,27 and 27 respectively. As shown particularly in Figure 4 sleeve portion26" is confined between spa/ced collars 28" and 29 so as to permitlimited end play between it andthe rod 27". Sleeve portion 26 issimilarly confined Vbetween collars 28 and 29 'on rod 27', and sleeveportion 26 is similarly confined between an abutment 28 and collar 29 onrod 27. f

Each of the rods 27, 27 and 27" is hydraulically actuated lengthwise andcontrolled-preferably by means such as will now be described. Each rodis fixed at one end in a small piston 30, 30 or 30, each pistonbeingclosely fitted for reciprocation within a cylinder 31, 31 or 31removably xed Within the head stock 11. The other end of each rodisilXed to a large piston' 32, 32' or 32 closely fitted for reciprocationin cylinders 33, 33' ..and 33, respectively, formed `in the head stock.The several cylinders 31, 3 1' and 31" are maintained flooded withliquid under pressure, supplied through a pipe 34rom an appropriatepressure source, such as a gear pump 35 of a well known type. Theadmission of hydraulic pressure to and eX- haust from the othercylinders 33, 3 3 and 33" are controlled by separate valves 36, 36 and36, respectively, of appropriate form.

The construction and operationof the three valves 36. 36' and 36" aresubstantially identical so that a description of one will suice for all.Each valve shown comprises a body los portion 37 formed as an integralpart of a removable end plate 3 8, and bored longitudinally to receive aplunger 39 closely fitted for `reciprocation therein. Each plunger 39 isreduced at 40 and provided with a piston head 41 at one end thereof.Three annular grooves 42, 43 and 44 are formed in the body portionencircling the plunger 39. Groove 42 of each valve communicates with anexhaust pipe 45, groove 43 with a duct 46, 46 or 46" leading tolone ofthe cylinders 33. 33 or 33, and, groove 44 with a pipe 47, 47 or 4 towhich hydraulic pressure may be supplied through an appropriate controlvalve 48,'such for instance as will be later described. A*

spring 49 interposed between abracket plate 50 and a collar 51 on theplunger 39 yieldably retains the plunger of each valve in the innerposition assumed by valves 36 and 36 in Figure 2. In this positioncommunication is established between grooves 42 and 43 through thereduced portion 40 of the plunger, so that the corresponding cylinders33 and 'plication-of hydraulic 33' are open to the exhaust pipe 45. Theapressure to any of the three pipes 47, 47 or 4g", however, istransmitted through groove 44gto the end of the l associated plunger 39,.and the plunger is forced outwardly against the spring 49 into the posiion assumed b'y valve36 in Figure 2. In this position of the' plungercommunication is established between grooves44 and 43- and thus pressureis transmitted through the duct 46 to the corresponding cylinder 33 1 .L

It will be notedI that rods 27, 27 and 27 are at all times urged towardthe left (Figs. 1 and 4) by the pressure maintained in the cylinders 31,31 and 31, so that when cylinders 33, 33 and 33" are open to exhaust thethree gears 21, 21', and 21'! are out of mesh' with the cooperatinggears 22, 22f and 227. Whenever yany of the cylinders 33, 33 or 33 areexposed topressure however the corresponding rod 27, 27 or 27 "isshifted toward the Tight(Figs. 1 and 4)A due to the greater size ofthese cylinders, and the corresponding gear l21, 21. or 21 is shiftedinto mesh with its cooperating gear 22,-

22 or 22". Thus with the plunger 39 of e valve- 36'. .ir-r the -outerposition of Figure 2, and the plungers of valves 36 and 36 in the Ainnerposition, rod 27" is in advanced position iwith gear 21" in mesh withgear 22, and rods 27 and 27 are in normal retracted position with gears22 and 22 out of mesh with gears 21'and 21.

Provision is preferably made' for retarding the advance of each rod 2,7,27 and-27'( toward the right (Figs. 1 and 4) without interfering withtherapid retracting move-` ment thereof toward the left, to thereby insuredisengagemet between one set of gears before the nerft set of gears arethrown into mesh. To this end each duct 46, 46 and 46 leading from thecorresponding valves 36, 36' and36 communicates with its respectivecy1inder"33, 33 or 33", through an annular chamber 52 formed in thecylinder wall in vsuch position as to be covered by the piston 32, 32,0,1532 when the piston is in in- ;nerretracted position. Cross ducts 53in each piston communicate with this chamber [when the piston isretracted, and a bleed duct 54 maintai-ns restricted communicationbetween ducts l53 and the interior of the cylinder. A larger duct 55,controlled by a check valvev 56, also connects ducts 53 withthe-interior of the cylinder. The arangement'is such that, with one ofthe pistons in retracted position such as isassumed by piston 32 inFigure V4, hydraulic pressure applied to the corresponding duct 46is'transmitted through chamber 52, crossducts 53, and bleed duct 54 tothe closed end ofthe cylinder 33,

and the piston is advanced at a very slow rate.

because 'of the restriction afforded by the bleed' duct. It is ofcourse/understood jthat underthis condition the checkV valve 56 isclosed by the pressure in the cross duct. The piston thus advances atthis low rate until the chamber 52 is uncovered by the end of thepiston, after which the piston advances quickly. Upon releasing thepressure in duct V46 the piston is free to return rapidly due to thefree passage of the liquid through the larger. duct 55, cross ducts 53,and chamber'52. i p

The control valve 48 hereinabove mentioned is shown in Figures 2, 5 and6. It comprises a substantially cylindrical body portion 57, supportedin upright position c by a pipe 69. Exhaust pipe 45 connects with lgroove 68 and consequently with groove 67.

Three intermediate grooves 70, 7 0 and 7 0 communicating with the pipes47,47 and 47, respectively, are controlled by the intermediate heads 62and 63. The ends of the bore58` and interior of theplunger 59 p areflooded with liquid under pressure supplied through a pipe 71 from thesupply pipe 34. This pressure isy transmitted I through ports 72 to 'theannular chamber surrounding the reduced portion 65 of the plunger. Thearrangement isl such that with the plunger 59 in the lower position ofFigure 5, groove. 7 0" is o'pen to the space surrounding the reducedportion 65, s o that pipe 4 is exposed to the pressure, inpipe 71; andboth grooves 70and 70' are open'to the space Surf' rounding .the reducedportion 64, soy that pipes. 47 and 47 are open to the exhaust pipe A theinner position shownand cylinders 33 and 33are open to the exhaust pipe45, so thatpistons 32 and 32 are-retracted andv gears 22 and 22' are outof meshwith arsV .21 'and 21. i Under this condition thespind1e\` 10isdriven at a slow rate. v

This condition lmaintains until the plunger 59 of the control valve, inits upward movement, approximates the position shown in .Figure 2.VVlhen thisoccurs groove 70" is opened to the space bsurrounding thereduced portion 66 and simultaneously groove 70 is opened'to the spacesurrounding the reduced 47', the plungers of valves 36 and 36 are inportion 65, so that the pressure in pipe 71 is applied to pipe 47a1'1dthe pipe 47 is simultaneously opened to exhaust. Groove 70 and 1 pipe 47remain open to exhaust. When this' d occurs valve 36' remains'unafectedbut the plunger 39 of valve 36 moves inwardly, under the action ofspring 49 while the plunger of -valve 36 moves outwardly,` so

that cylinder 33 is' opened to exhaust and piston 32" and rod 27 areretracted rapidly to thereby withdraw gear 21" from gear 2 and so thatthe cylinder 33 is exposed to pressure and piston 32. and rod 27advanced slowly in the manner hereinabove described l until gear 21 isultimately engaged with gear 22. The spindle 10 is thus driven atintermediate speed. This condition maintains until the .plunger 59, inits upward advance, approximates the position shown in Figure 6. Whenthis occurs groove 70 is opened to the pressure in the space surroundingthe reduced portion and simultaneously groove 7 0 is opened to exhaustthrough the space surrounding the reduced portion 66, the grooveremaining open to exhaust through the space last mentioned. This causesa rapid retraction of the piston 32 and rod 27 with a consequentdisengagement of gears 22. and 21 and aslow advance of piston 32 and rod27 to ultimately effect engagement of gears 22 and 21, in the mannerhereinabove described. The spindle 10 is then driven at high speed. Thiscondition maintains until upward movement of the plunger 59'. ceases.

Provision is made in the lathe shown for automatically operating thevalve plunger 59 in accordance with movements of the tool` carriage 16along the cross-slide 14. To this J end a control rod 73 is connected tothe plunger 59 throughanf'appropriate link 74. The control rod 73 isguided for vertical reciprocation in the lower end of the bore 58 and inan appropriate bracket 75 fixed to the head stock, and carries at itslower end a Vplate 76 having a cam slot 77 therein. A disk 78, fixed toone end of and driven by a shaft 79, carries a crank pin 8() closelyfitted for travel within the slot 77. The shaft 79 extendsdiagonallyacross the lathe within the base thereof, as indicated inFigure 1,` and at its other end carries a driving gear 8l meshing withand driven by a smaller gear 82 on a vertical shaft 83. (See Figure '7.)

Shaft 83 is driven from a shaft 84 (Fig. 1).'

plurality of teeth, to thereby facilitate reestablishing a predeterminedangular relation between the shaftp84 and gear 87 upon reclosing theclutch. The clutch is controlled by an appropriate handle 92. y Thegears 81 and 82 are preferably so proportioned as to effect only 'apartial rotation of the crank disk 78 during travel of the tool carriage16 throughout its normal range.' The cam slot 77 shown is curved for4the major portion of its length with a radius of curvature substantiallyequal to the radius ofcurvature of the path ofthe crank in 80, theremainder of theA slot being .su stantially straight and transverselyextended. 'By shaping the slot in this manner the rod 73 and valveplunger 59 move through a very short distance, from the position shownin Figure Figure 2, while the crank pin -travels through agrather widearc; and while the crank pin travels through a rather limited arc, fromthe position of Figure 2 to the position of Figure 6, the rod 73 andplunger 59 travel through a distance greater than the first. The purposeof this arrangement will hereinafter appear.

`During normal feed movements of the tool carriage 16 the motion of theplunger 59 of the control valve is so slow as to permit ample time for,the colnpletion of each of the successive gear shifting actionshereinabove described, but when the shaft 79 isrotated rapidly by hand,it is highly desirable that movement of the valve plunger 59 betemporarily arrested at each gear shifting position thereof in order tovpermit the completion of each gear shifting operation. This isaccomplished in this instance by the use of interlocking mechanism suchas will now be described. Three recesses 93, 93 and 93 are formed in theside of the rod 73 for cooperation with the plunger 39 of the valves 36,36 and 36", respectively. The arrangement of the recesses is such thatin the lower position of the valve plunger 49 (Fig. 5) the .exposed endof plunger 39 of valve 36" projects into the recess 93, and thusprevents the rod 7 3 and plunger 59 from moving upwardly beyond theposition shown in Figure 2, until the plunger 39 of valve 36" has beenshifted inwardly in the manner hereinabove described to initiate theoperation of the gear shifting mechanism. Inthe position shown in Figure2the recess 93 has become aligned with the end of plunger 39 of valve36', so that the end of plunger 39 engages therein as it is forcedoutwardly substantially simultaneously with the inward shifting ofplunger 39 of valve 36, in the manner hereinabove described. Theengagement of this plunger 39 in recess 93 prevents upward movement ofthe rod 73 and plunger 59 beyond the position shown in Figure 6, untilthis plunger has been shifted inwardly to kinitiate the next gearshifting operation, at

5 to that of which time the plunger 39 of valve 36 moves circular flangehydraulic transmission including a variable' displacement pumpt94 ofY awell known type and a similar variable displacementhydraulic (motor 95.The pump-shown is fullydescribed in my prior Patent No. '1,558,002issued October 20, 1925. It will therefore suffice heife to state .thatthe saine is driven at constant speed through appropriate means, suchas'a pulley 96, and that the'displacement thereof may be-varied fromzero to a maximum., by longitudinal adjustment of a controlstem 97 tothereby regulate the rate and' direction of flow Vof liquid in pipes 98and 99, constituting the two sides of `a hydraulic circuit fed thereby.-The -control stem 97 in this instance is actuated and vcontrolled-bymechanismv to be hereinafter described. The essential elements of themotor- 95 are substantially identical with those of the pump. The motorincludes a cage 100 rotatably supported by ball bearings 101 and 102 andkeyed. tothe end of' the shaft 20. Bearing 101 is supported, uponan-inturned 103 forming a part of the removable end plate 38 of the headstock and vbearing 102 is supported within arigid bridge piece 104within the head stock. The forward endof shaft 20, is supported in aball bearing 105 disposed withina cup element 106 removably iixed withinthe forward end ofthe head stock. The cage -100 is driven by a circularseries of piston and cylinder assemblies 107 -m'ounted for rotationabout a pintle 108. The pintleY is carried by an upright arm 109,rockably supported at its lower end upon ashaft 110 firmly anchored inthe rear` wall f the head stock. The pintle 108 is provided'withj'theusual passages 111 and 112 which communicatewith the usual ports 113 and114, respectively, formed in the top and bottom of the pintle forcooperation with Y the piston and cylinder assemblies in the usualmanner. respectively, with passages 115 and 116 formed in Athearm 109and whichI in turn communicate with pipes 117 and 118 con-- stitutingAtwo4 sides" of fthe motor circuit. Pipes 98 and 99 from'the pump areconnected vwith pipes 117 and 118 from the motor through two Ycontrolvalves 119 and 120,'such Y for instance as will be hereinafterdescribed.

These valves are connected through pipes 121 and 122 to complete thecircuit between the Passages 111 and 112 communicate,

pump and motor through which the motor is driven. The displacementV ofthe motor 95 is re lated by swinging the arm 109 to there y shift thepint e 108 and thus regulate the degree of eccentricity of the pintlewith respect to the axis of rotationv of-the cage 100. This isaccomplished in this instance by a hydraulically operated stroke changemechanism of a well known type, such for instance as that shown inFigure 2 This mechanism includes a cylinder 123 ed to the .end of thehead stock and enclosing a hollow piston 124 reciprocable therein. iston124 is connected to the arm 109 thr ugh appropriate 80 linkage 125 andis. longitudinally bored, as at 126 to receive ahollow plunger 127reciprocable therein and controlled by avstem 128. An annular chamber129 surrounding the piston`124 is supplied withliquid under pressurethrough' a pipe 130, connected with pipe -34 leading from the gear pump35. A similar chamber 131 surrounds the plunger V127 and communicateswith chamber`129 through a duct 132. The plunger 127 is further pro- 90vided with end heads 133 and 134 which control ducts `135 and 136 in the.piston 124 leading to the opposite ends of the cylinder 123. Thebore126 of the piston is open to exhaust through a pipe 137 connectedwith exhaust.V 95 pipe 45. The ducts 135 and 136 are normally closed 'bythe end heads 133'an/d 134, respectively. The arrangement is such'thatwhen the plunger 127 is shifted through a definite distance toward theright, the left end of the 100 cylinder is exposed to pressure throughduct 136, chamber 131, duct 132, chamber 129 and pipe 130, and the'right end of the cylinder is openedl tojexhaust through duet 135, bore126 and pipe 137, so that the piston immedi- 10.5 ately moves toward theright through a corresponding distance, until the ducts 135 and 136 areagain closed by the end, heads 133 and 134. The arm 109 and pintle 108are thus shifted through a distance corresponding-'to 110 the movementof the Aplunger 127 and stem `Y128. A similar reverse action occurs w enthe stem 128 is shifted toward the left. he 'stein 128 is actuated andcontrolled by mechanism which will'beehereinafter described. 1 15lrovisio is made in the lathe shown for bringing the shaft 20 to restduring each gear shifting sta e to'facilitate the gear shiftingoperation. echanism for this purpose is shown in Figures`1,.3 and Thismecha-T129 nism includes the valve 120 hereinabove melig; tionedwhich isinterposed within the' pump#` motor circuit and is controlled. by thegearcontrol rods 27, 27 and 27" in a mannerto be later explained. lYThis valve includes a 125 housing 138 bored Vto receivea plunger 139reciprocable therein. i The plunger is reduced at 140 and 141 to formspacedheads 142,

cross ducts 146 therein maintain communicaformed wi tion between thespaces surrounding the reduced portions 140 and 141. An annular groove147, always open to space 141, communicates with pipe 122; a similargroove 148, controlled by head 143, communicates with pipe 118; and athird groove 149, controlled by head 142, communicates with pipes 117and 121. A spring 150 yieldably maintains the plunger 139 in theposition shown in Figure 8, in which position the head 143 covers thegroove 148, and thus substantially blocks the flow in pipe l118 tothereby resist o ration of the motor 95. In this position o the plungercommunication is established between pipes 121 and 122 through the ducts145 and 146 so that the pump circuit is effectivel by-passed and t epressure in pipe 117 lea ing to the motor is destroyed. It will benoted' that head 143 is somewhat wider than the glroove 148 but it ispreferably t gashes 151 about the periphery thereof'designed to providefor some leakage of liquid from the-groove 148, to thereby avoidexcessive pressures in the pipe 118 whenthe plunger is suddenly shiftedinto the 'tion shown in Figure 8. The plunger 1s movable against theaction of spring 1 50 into the position shown in Figure 3. In thisposition pipe121 isopen to pipe 117 through the groove 149 and pipe 118is opento pipe v422 through thel ductsV 145 and 146, and the motor 95 isconnected in driving relation with the ump 9 4. v v

e 2valve plunger 139 is coptrolled by three pushpins 152, 152 and 152"closely tted for lengthwise reciprocation in sepa.- rate bores 153, 153and 153" formed in the i head of the valve housing. Pipes 154, 154 and154, leading from the respective bores,

are controlled by valves 155', 155', and 155, respectively. Each of thevalve'scomprises a body portion 156 formed as an integral part of onerofthe/cylinders 33, 33 or 33 and bored longitudinally to receive a plungerhaving spaced heads 157 and 158, connected by a reducedportion 159, anda square stem 160 adapted tol roject transversely into the associatedcylin er. The space surrounding the reduced portion 159'is supplied withliquid, under pressure througha pipe 161, connected with the pipe 34leadmg from the `gear pump' 35. An annular groove 162, controlled bythehead 157, communicates with one of the pipes 154, 154 or 154" and asimilar groove 163 communicates througlia pipe 164 with'the exhaust pipe45. \A spring 165 yieldably retains each vvalve in'the position assumedVby valves 155 and 1 55 Figures 1 and 3 'with the stem 160 projectingintolthe path of reciprocation of one of the plstons 32,'

32 or 32"., In the position of valves A-155 and 155 pipes,154 an'd 154are open toexhaust through pipe'164 and the corresponding push' pins 152and 152 are retracted. The front face of each piston'32, 32 and 32\isbevelled oi' as shown at 166 for coaction with the bevelled end 167 ofeach stem 16() so that whenever one of the pistons is advanced into theposition assumed by iston 32" in Figures 3 and 4, the stem 160 is orcedoutwardly and the corresponding valve plunger shifted into the positionassumed by valve 155" in Figure 3. In this condition of valve 155 pipe154" Ais exposed to the pressure in pipe 161 and the corresponding pushpin 152 is advanced, thereby shifting KIN.the plunger of valve 120 intothe position shown in Figuref3.

A brief description of the operation of the several parts thus fardescribed will now be given. With the tool carriage 16 in retracted posiion the main control valve 48 assumes the pos tion shown in Figure.5 lsothat pipe 47 is exposed to pressure and pipes 47, and 47 l are open toexhaust, and so that rod 27 has been advanced by the pressure incylinder 33 and the other rods 27 and 27 are retracted by the pressurevin cylinders 31 and 31. Thus gear 21" has been advanced into mesh withgear 22" by the thrust -of collar 28" against the sleeve portion 26" offorked arm'25", and gears 21 and 21 have been withdrawn Jfrom engagementwith gears 22 and 22', respectively, by the thrust of collars 29 and 29against the sleeve portions 26 and 26 of forked arms 25 and 25. With thepiston 32" thus advanced the stem 160 of valve 155 is held in the outerposition shown in Figure 3 so that pipe 154" is exposed to pressure andthe valve 120 is held in the 'position shown in Figure 3. Fluid pressureis thus transmitted from pipe 121 to pipe 117 todrive the moto 95, theHuid exhausting from the motor through pipes 118 and 122. vThe shaft 20is ipe 47 is then exposed A pressure in cylinder 31" and so that'cylinder 33 is exposed to pressure causing rod 27 to advance. ItA willbe noted that' during the retraction of rod 27 the forked arm'25 and ear21" remain unaffected until' collar 29" as made contact with the sleeveportion 26" this idle movement of rod 27 and piston 32 being suicient torelease :the'stem 160 of valve 155 and thusrpermit the plunger of thisvalve to assume the retracted position and thereby open pipe 154" to theexhaust pipe 164. The pressure thus released in bore 153" permits theplunger of valve A to assume the position shownin Figure 8. When thisoccurs, the exhaust pipe 118. Lfroml is advancing slowly7 in the mannerherein# above described causing the collar 28 toengage the sleeveyportion 26 and ultimately forcing the gear 21 Just before the rod 27reaches a fully advanced position, the stem`160 of valve 155 is forcedoutwardly by the piston 32', thereby exposing the pipe 154 to-pressureand causing the plunger ofgalve 120 to reassunre the position of Figure3 under the thrust of the push pin 152. This reconnects the motor indriving relation with the pump so that shaft 20 is again rendered activeand spindle 10 is driven at moderate speeds through the inter- A mediategear 21.

' causing the withdrawal of lgear 21 from gear This condition' normallymaintainsV until, under the advance of the tool earriage,. control valve48 arrives at the position shown in Figure 6, exposing'cylinder 33 topressure and opening cylinder 33 to exhaust. Rod 27 then advances slowlyan grod- 27 retracts,

22 and engagement of gear'21 with gear 22 to effect a high speedoperation of the spiny' dle. During the retraction of rod 27 'and piston32 stem 160 of valve 155 is released and pipe 154 opened to exhaust,permitting valve to reassume the position shown in Figure 8, to therebybring the motor to rest in the manner just-described The motor andspindle again remain .at rest until the stem of valve 155 'is forcedoutwardly by the advance of piston 32 thereby exposing thel pipe 154 topressure, and forcing the plunger of control valve 120 into the positionof'Figure 3, bythe thrust of push pin 152. The action of the motor isthus renewed. and the driven at high speed through the high speed gear21.

It will be noted that, because ofthe exceedingly slow motion of theplunger. 59 of the control valve 48,- in'the machine shown, an

extremely accurateformation of the piston heads 62 and 63 andcooperating grooves 70,

, 70 and 70 is required to insure proper functioning of the partscontrolled thereby.'

For instance as the' valve plunger 59 apf proaches the position shownin-Fi-gure2' should be opened to the space begroove 70 -tween heads 62and 63 simultaneously vwith the opening of groove 70 to the spacesurrounding the, reduced 'portion 68. Should' thegroove 70 be opened tothe space-surrounding the reduced portion 68 before the groove 70 isopened heads 62 and 63;, the rod 27 might be A-retracted, the stem v160of valfve 155 released, thevalve 120 shifted into the position showninto mesh with gear 22'."

to the spaceV between L in FigureS, and the spindle 10 thus actuallybrought to rest ally established between pipe 47 and the pressure pipe71. Should this occur thermachine would remain at rest andthe cycle ofoperations above described would remain uncompleted. To guard againstthis contingency provision is Apreferably made for retarding theadjustment of valve 120 from the active position shown in Figure 3 tothe blocking position of Figure 8. This is accombefore communication isactuplished in this instancel by introducing a throttle valve ofvappropriate form Awithin each of the pipes 164 by which any desiredresistance to the escape of liquid from anyof the bores 153, 153 or'153may be had and the rate of adjustment of the valve 120 toward blockingposition correspondingly regulated.`

Provision is made in the machine shown for effecting a substantiallyuniform variation in the speed of operation of the spindle 10 betweensuccessive gear shifting periods and to this end use is made of thevariable displacement characteristics of the pump and motor. .-In thisinstance two cams 171 and ,172 are provided, cam 171 being designedtoregulate pump displacement and cam 172 being designed to regulatemotor displacement. Both are driven from the tool carriage 16 and areshown fixed to the vertical shaft 83, hereinabove mentioned. Provisionis also made for manuall adjusting these cams simultaneously throug anappropriate hand wheel 17 3 fixed to shaft 83. Cam 171 cooper ates withapin'174 freely rotatablewithin the arm 175 of a lever rockably supportedally connected intermediate its ends to the control stem 97 ofthe pump.lThe other end 181 of the floating lever is connected through a link 182,bell-cracnk 183, and link 184 with a hand lever -J185 under the controlof the operator. Cam 172 cooperates with a pin 186 freely rotatable inone end of a lever 187, rockably supported at its'other end upon a pivot188. n Lever 18,7 is connected through a link 189, bell-crank 190, and"link 191 with the-control stem 128 of the motor. Appropriate springs 192and 193 hdld the pins 174 and 186 against their respective cams 171 and17 2. Both pins 174 and 186 are similarl mounted so that a descriptionof one ,will su lice for both. As indicated in FigureilO pin 17 4projects rigidly from one end ofj a spool -194 supported in spacedanti-friction bear-i in 195 and. v196 within an appropriate socket 197 Yformed inV the endof the lever arm i i I It will be noted that eam'171`is formed. with lthree sharp rises rv, and and that -cam 172 is formedwith threesimilar rises y, y and y. Rotation of the cams and lllmovement Aof the plunger 59 and control valve 48 are so coordinated thatwhen this plunger is in the position of Figure 5, pins 174 and 186engage their respective cams at points adjacent thenbases of the rises wand as this plunger approximates the position 'shown in Figure 2, pins174 and 186 pass over the respective rises a2 and y to the basesthereof; and as this plunger approximates the position shown in Figure 6the pins pass over the respective rises as and gf.

With the pin 174 at the top of any of the rises az, or v and the pin 186at the top. of the corresponding rise y, y or y the pump is in maximumdisplacement condition and the motor in minimum displacement condition`so that the motor is then operated at maXimum speed. With the pin 174 atthe base of any of the rises m, ze or fr and the pin 186 at the base ofthe corresponding rise y, y -or y" pump displacement isv reduced andmotor displacement is at a maximum, thereby efecting operation of themotor at a relatively slow speed. The motor speed is thus suddenlyreduced from a maximum to a mini-Y mum as the pins pass from top tobottom of each pair of rises 2/ and -y and this occurs during each gearshifting period. In the machine'shown there are only twp gear shiftingperiods andthe cams do' not make a complete rotation so that the sharprises w and y never actually come into play. The relative change in thespeed of the motor, effected by changing the displacement of pump andmotor, is preferably the same as the change in relative speed betweenthe shaftA 20 and spindle l0, effected by ,each gear shifting operation,so that the speed of the spindle is substantially the same immediatelyafter each gearshiftin operation as it was immediately prior lto tatgear shifting operation.l Actual variation in spindle speeds thus occurs onl` between successive gear shifting periods y adjusting pump andmotor dis.

placements through the action of the cams.

In the machine shown cam 171 is formed i ywith a' gradual rise p, p andp leading from the base of each abrupt rise 4v and ne, ands nerging intoa concentric portion l c, c and c. which continues to the top of thesucceeding abrupt rise, so that the pin 174, following this contour,causes a gradual increase in pump displacement and thereafter maintainsthe pump at maximum ,displacement until the following gear shiftingperiod. Cam 172 is formed with a concentric portion (1,03 and dleadingfrom the base of each abrupt rise y, y and y" and merging into a gradualrise m, m or m which continues to the top of the succeeding abrupt rise.Each concentric portion d, d

and d is substantially coextensive with the corresponding gradual risep, p or p, and` each gradual rise m,-m and m is coex'tensive with thecorresponding concentric pordisplacement is maintained 'at a maximum,

motor displacement is gradually reduced. Thus during each period betweensuccessive abrupt rises on the cams the speed of the .motor is graduallyincreased, lirst by the gradual increase in pump displacement andthereafter by the gradual reduction in motor displacement.

For purposes of explanation let it be assumed that the machiiie is set.up for producing a facing cut upon a piece of work a, having an outsidediameter of twenty inches, by the action ot the tool 19 which is slowlyadvanced across the face of the work, to substantially a. quarter of aninch from the center thereof, as the work is rotated with and by thespindle-10. It is quite obvious that in order to maintain the actualcutting speed substantially constant in all positions of the tool 19,the speed of rotation of the work must increase inversely as thedistance between the tool and center of rotation. Let it also be assumedthat the pump is driven at constant speed, that pump displacement isstroke to four tenths. This variation aloney will provide an increasein'motor speed of about three and one third' times its slow speed. Letit also be'assumed that each pair `of gearsj2122, and 21-22 will providea speedV ratio between shaft 20 and spindle 10, three andv one thirdtimes as great as vthe ratio provided by the preceding pair. As the tooladvancesinwardly fromthe periphery of the work toward the center 'ofrotation, the speed of the'motor is gradually increased in the mannerdescribed, and at a rate inverselyproportional to the distance of thetool from the center of rotationantil a speed has been attained threeand a third times the original speed. At this point the Erst gearshifting operation occurs, gears 21 and 22 being disengaged and gears 21and 22 engaged,to thereby increase the ratio betweenv attainedimmediately prior to the first gear shifting period. At this point gears21 and 22v are automatically disengaged and gears 21 and 22` engaged andthe ratio between increased as the tool advances un;

. ment of the cams traced by thetool upon the work.

...b o enin the w Y P g ator in Ireestablishing the shaft l and spindle10 a ain increased three and one-third times; an the speed of the motoris again simultaneously reduced to its original speed. Thereafter themotor speed again gradually increases in the manner described until thetool reaches the end of the cut. With the parts proportioned andcorrelated in the manner described the speed of rotation of the work isincreased gradually from about nineteen'revolutions perminute t0 aboutseven hundred revolutions per minute thereby maintaining a uniformcutting speed of about one hundred feet per minute in all positions ofthe tool. f j

Whenever a new tool is brought into play, either by rotation ot theturret a17 or by actual replacement of the tool 19, adjust- 171 and 172relative to the carriage 16 is permitted by withdrawal and adjustment ofthe) pinion 88 with respect to the rack 89. Such an adjustment isdesirable in order to compensate for the variation in location of theactual cutting edge of the new tool. To facilitate setting up themachine for each new tool and work, an appropriate graduated scale 2001s provided on the face of the cam 171.', which cooperates with a fixedpointer 201, to indicate the proper setting of the cams to correspondwith the distance of the cutting edge ont the tool from the center ofrotation or the work. rlhe scale shown is graduated in inchescorresponding to the diameter of the path "in the event that the workcalls for the use of' a toolpoperating on a fixed diameter, such as aboring to l 15, the cams 1 71 and 17 2 may be disconnected from thecarriage 10,

clutch 85, and thereater adjusted to a position corresponding to thediameter of the hole to be bored, and as indicated on the scale 200.Proper adjustment of the cams will insure rotation of the work at thespeed appropriate for the boring operation. Aiter Athe boring operation1s completed the clutch is again closed. fact that the clutch is asingle tooth rather than a multiple tooth clutch assists the oper-,relation which eX- isted Abetween the cams and carriage prior to theripening of the clutch. j

From the foregoing it will be noted that pump .displacement is normallyregulated by the setting or operation of the cam 171'variv55" ation inpump' displacement being e ected 'by movements of the floating lever theaction oi theilever arm 175. be noted that pump displacement be variedby adjusting .the hand lever` 185,

to thereby adjust the 'end 181 ofthe oating lever 180 and consequentlythe pump controll stem'97.' yThe -hand lever 185 remains xed duringnormal'operation of the machine. This 'lever is adjusted only whenspecial circumstances such as softer or harder 207 and 208,`connected byThe `v'Wgashes 151 in the head 143 of valve 120 y.

work material require automatic o eration of the machine at s s otherthan t e speed assumed atnorm Provision is also made or stopping,starting or reversing the machine at the will of the operator. In thisinstance the valve 119 hereinabove referred to is provided for thispurpose. This valve comprises a cylindrical housing 205 longitudinallybored as at 206, to receive a plunger having two spaced heads 209. Theopposite ends/of the bore 206 are permanently connected through apassage 210, which in turn comm nicateswith pipe 98 normallyconstituting t e return side of the pump circuit. A groove 211,connected with pipe 121, is controlled by piston head 207 a similargroove 212, connected with pipe 122, is controlled bypiston head 208;and an' intermediate groove 213, connected with the pipe 99,constituting the working lsideoi the pump circuit, is always incommunication with that space between the heads 207 and 208. Thearrangement is such that when the valve plunger is in the left extremeposition shown in igure 3, pipe 99 is open to pipe 121, and pipe 98communicates through passage 210, Vwith pipe 122. The motor is thendriven by the liquid discharged from the pump through pipes 99, 121, and117. When the valve plunger is inthe right extreme position of Figure.8, pipe 99^is open to pipe 122 and pipe 98 is open to pipe 121, so thatthe direction of ow in pipes 121 and 122 is reversed and the operationof the motor and the entire machine is reversed. To stop the machine thevalve plun er is shifted into an intermediate position w erein pistonhead 208 covers groove 212 to thereby block the iiow of liquid .from themotor throng pipe 122, and wherein piston head 207 assumes a ositionintermediate the groove 211 to there y open communication between pipes98 and 99 and thus by-pass the pum circuit.I The piston head -208 ispreferab y gashed as at 214, ,in a manner similar to th for asimilarpurpose. ,The plunger of valve 119 is controlled' by a stem 215,connected through a link 216, bell-crank 217, and link- 218 .with anappropriate hand lever 219 under. I

the control of the operator; j

Variouschanges may be made in the ema reduced portion h los 125 l mechofa pump, avariable displacement h draulic. motor driven by said pump,means or regulating motor displacement, change speed mechanism betweensaid motor and member, means for adjusting said change speed l mechanismto vary the speed ratio between said motor and member, and unitary meansfor controlling said displacement regulating means and said adjustingmeans.

.3. The combination with a driven member of a variable displacementpump, means for regulating pump displacement, a hydraulic motordrivenwby said pump, change speed mechanism between said motor andmember, a control element, and means responsive to said control elementfor operating said regus mechanism in pre etermmed sequence to va thespeed of said member.

4. i e combination with a driven member, of a vaiable displacement pump,a variable displacement hydraulic motor driven by said pump, means forregulating -pump displacement, means for-re lating motor displacement,change spe mechanism driven by 36 said motor for driving said member,means for adjusting said change speed mechanism to thereby vary thespeed ratio between said motorandmember, a control element, and

means responsive to the position .of said control element forcontrolling both of said regulating means and said adjusting means.

5. The combination with a driven member,

l of a variable`displacement pump, a variable displacement hy raul icmotor driven by said pump, meansv for regulating pump displacement,means for regulatin motor displacement, change s ed mechanism driven bysaid motor for digieng said member, means for adjusting said changespeed mechanism, and means for operating both of said regulating meansand said adjusting means in predetermined uence to thereby vary thespeed of said mem r.

6. The combination with a of` a variable s including a hy raulic` motor,change speed driven member,

' mechanism driven by saidmotor for driving ing and abruptly saidmember, means coacting with said hydraulic transmission forgraduallylincreasdecreasing the speed of said motor alternate and meansfor adjusting said change speed mechanismto increase the speed ratio`1between said motor and members during each abrupt reduction in thelspeed of Y said ,motor 'to thereby effect a gradual increase in thespeed of said member throughoutawideran Q A 7. The combination with adriven member, of a variable s eed hydraulic transmission including ahydraulic motor,.chang e speed mechanism drlven by said motor fordriving lating means and for ad'usting said change second4 mem edhydraulic transmission.

motor, a change speed mechanism driven by A said motor for driving saidmember, means automatically operable to adjust said chan speed echanismat predetermined interva and means for rendering saidmotor momentarilyinactive during each adjustment of said change s eed mechanism.

9. The com ination of a rotary work holder,-a tool-carrier movabletoward and from the axis of rotation of said first named member, avariable speed hydraulic transmission for driving said rotary workholder, and control mechanism for saidv transmission automaticallyoperable to regulate 4the speed of said rotary work holder in accordancewith the position of said tool carrier.

10. The combination ofa rotary work holder, a tool carrier movabletoward. and from the axis of rotation of said work holder, a variablespeed hydraulic transmission for driving said rotary member saidtransmissionl including a variable placement hydraulic motor, ing meansfor said motor responsive to the position of said tool carrier relativeto said axis of rotation for regulating the speed ofl said motor.-

11. The combination of a rotary member, a second' member movable towardand from the axis of rotation of said member, means including twovariable speed transmissions for driving said rotary member, separateregulating means for each transmission and means resp nsiveto themovement of, said r for controlling bothof said regulating means.

, 12. The combination of a rotary work holder, a tool carriage movabletoward and from the axis of rotation of said work holder, a variablespeed drive lfor said work holder lincluding a hydraulic variable speedtransmission and a variable speed gear transmission, and meanscontrolled by said carriage for adjusting both of said transmissions tothereby regulate the speed 'of said work holder.

13. The combination of a rotary work holder, a tool holder movabletoward and from the axis of rotation osaid work holder, driving meansforsaid work holder comprising a variable displacement hydraulic motor anddisplacement regulatand a variable speed gear transmission, and

tool holder for regulating motor displacel ment and for adjusting saidtransmission to thereby regulate the speed of said work holder.

14. The combination-of a driven member, driving means therefor includinga variable displacement hydraulic motor and a variable speed geartransmission, a control element,

Ameans responsive to movement of said control element for regulatingmotor displacement and means responsive to movement o said controlelement for adjusting said transmission.

, speed gear transmission,

15. The combination of al driven member,

driving means therefor including a variable my ,name this 18th day ofApril, 1927.

WALTER FERRIs.

